三级串联垂直潜流人工湿地的脱氮性能及微生物学特征

探究了3种水力负荷(HLR)下三级串联垂直潜流人工湿地(T-VFCWs)对农村生活污水的处理效果,并解析了系统中的氮素转化机制。结果表明: 当系统HLR由0.10增至0.20 m³·m^-2·d^-1时,T-VFCWs始终保持着对农村生活污水高效的处理效果,系统出水水质满足《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。T-VFCWs中顺次连接的3个VFCW单元(标记为V-1、V-2和V-3)在限氧环境下因其进水水质的差异可形成各自不同的氮素转化途径,并通过协同作用实现系统的高效脱氮。当T-VFCWs在试验期间连续运行时,V-1、V-2和V-3中主要的脱氮途径分别为短程硝化/反硝化作用、基于亚硝化的全程自养脱氮(CANON)作用和反硝化作用,上述3单元对进水中总氮(TN)和NH₄⁺-N去除的贡献率分别为(51.3±4.4)%和(63.7±2.6)%、(30.9±4.8)%和(35.5±4.5)%、(17.8±5.0)%和(0.8±0.1)%。该研究可为组合式人工湿地的研发及工程化应用提供科学依据和技术支撑。

Nitrogen removal performance and microbiological characteristics of a three-stage series of vertical flow constructed wetlands

In this study, the treatment performance and underlying molecular mechanisms of nitrogen transformation in a three-stage series of vertical flow constructed wetlands (T-VFCWs) treating rural domestic sewage were investigated at three different hydraulic loading rates (HLRs). Specifi-cally, the T-VFCWs composed of three sequential vertical flow constructed wetlands (termed V-1, V-2 and V-3), which were built according to the topography. The results showed that high pollutant removal rates could be achieved when the T-VFCWs was operated to treat rural domestic sewage, even though the HLR increased from 0.10 to 0.20 m³·m^-2·d^-1. Effluent quality of the T-VFCWs could reach Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) class A standard. Regarding to the T-VFCWs operated under the oxygen-limiting conditions, three different pathways for nitrogen transformation could be respectively formed in V-1, V-2 and V-3, owing to the specific influent quality of each subunit. Consequently, the T-VFCWs were effective in nitrogen removal as a result of the collaboration of the three subunits. When the T-VFCWs ran constantly during the test, nitrogen removal in V-1, V-2, and V-3 respectively relied on the nitritation/denitrification process, the completely autotrophic nitrogen removal over nitrite (CANON) process, and the denitrification process. The contributions of three subunits for total nitrogen (TN) and NH₄⁺-N removal were (51.3±4.4)% and (63.7±2.6)%, (30.9±4.8)% and (35.5±4.5)%, (17.8±5.0)% and (0.8±0.1)%, respectively. This study could provide scientific basis and technical support for the research and the engineering application of hybrid constructed wetlands.